There is no prescribed BHU UET 2018 syllabus so it will be based on your 11th and 12th only so it is advisable to revise the same properly and once you are done with these you can refer to previous year papers for your practice.

Below is the link provided from where you can download them -

http://bhuonline.in/old-qus-paper-entr.html

Good Luck!!!